Sonic the Hedgehog is the first title in the Sonic The Hedgehog series, and the first appearance of Sonic The Hedgehog. The game's original programmer was current Sonic Team leader and series creator Yuji Naka, and the planner was Hirokazu Yasuhara. The gameplay was faster than any other game before it and amazed many people at launch. This was due to the Genesis's Motorola 68000 processor, whose basic speed and ability to handle 16-bit numbers gave it incredible speed compared to its predecessor, the Master System
Sonic the Hedgehog plays very similarly to other platformers, in which the titular character must get to the end of the stage in the allotted time, while collecting the items along the way. Essential to the gameplay are the Power Rings the player collects along his/her way in each level, a feature which would become one of the defining characteristics of the series. These items are regularly placed around the level map and serve multiple functions. First, the player collects rings to protect Sonic. As long as they have at least one ring, the player will not lose a life when injured. Instead, when hit, up to 20 of the rings the player has collected will fly outward and scatter around the immediate area for some seconds, some of which can then be retrieved before they disappear. If the player runs into an enemy without a single ring, they will lose a life. If the player collects 100 rings they will gain a life, and gain an additional life for every 100 rings after that, provided the rings are not lost.
If the player has at least 50 rings at the end of an act, a Warp Ring will float above the finishing sign which can be jumped through to enter one of the Special Zone (this excludes the final act of a stage, when Sonic will enter a boss fight). At the end of each act, the total number of rings the player has is multiplied by 100 and added to the player's score. During the score-tallying, the player can also jump through the air to find hidden emblems which can range from 100 to 10,000 points. This was the only console Sonic where the player could not get more lives by collecting over 200 rings (this is the only 16-bit title where it is impossible to obtain 300 rings in a single stage).
Also scattered throughout each level are monitors (or TVs as some call them) which, when broken by the character, reward the player with one of a variety of bonuses. These include a shield which will protect Sonic from a single hit, a 10-ring bonus, an extra life, temporary invincibility (accompanied with a temporary change in music), and "Super Sneakers", which give the player a temporary speed boost (and increase the tempo of the music for the duration). The item monitors have become another long-lasting feature in the series, though they have been changed to bubble-like containers that can float in later games.
Despite the various types of protection available, neither the shield, rings, nor invincibility will prevent the player losing a life if Sonic is crushed (by a trap or between a wall and a moving platform), drowned, runs out of time
(each act has a ten-minute time limit), or falls into a bottomless pit.
Progression through the game is made easier for the player by lamp post that act as checkpoints. When Sonic passes a lamp post, the spherical top spins around and its color changes from blue to red, and the next time a life is lost, gameplay will restart at that point rather than at the beginning of the act. In the Japanese version, if a checkpoint is activated and a life is lost as a result of running out of time, the time at the checkpoint will reset to 0:00.
Hazards the player experiences include a wide variety of "badniks" - these appear as animals trapped inside mechanical bodies which are released the moment the player hits them. Each badnik takes one hit to destroy, but they vary greatly from Zone to Zone; some will walk in a set path, others will try blasting the player, and some cannot be avoided at all. The player must also avoid rows of sharp spikes, cliffs, and elaborate death traps. There is also the threat of drowning (in Labyrnth Zone and the third act of Scrap Brain Zone which acts contained water), as the player can only survive approximately 30 seconds underwater (locating air bubbles can extend this).
As long as Sonic has some of these, he won't lose a life if he takes damage. Sustain a hit and all your collected Rings will scatter, giving you a brief opportunity to grab a few back before they disappear. (Rings will not protect Sonic from getting crushed by a trap, falling below the level or running out of time. all of which result in instant death.) A 1up is awarded for every 100 Rings collected and each Ring is worth 100 points at the end-of-Act score tally.
In each stage, you'll find a number of these power-up bearing monitors. Pop them open with a spin to procure one of five power-ups:
Super Rings - Worth 10 Rings
Sheilds - Absorbs one hit
Power Sneakers - Temporary speed increase
Invincibility Boosts - Temporary invincibility
One-Ups - Gives Sonic an extra life
Sai Start Marker
These hold your place in a stage: should you lose a life, you'll start back at the last Start Marker you crossed.
Round bumpers found only in Spring Yard Zone and the Special Zone. Bounce off one for 10 points, up to 10 times for a total of 100 points. (They stop dispensing points after the tenth hit.)
Leap onto the broad side to catapult Sonic into the air. The yellow ones send him flying a short distance and the more powerful red ones send him farther.
Don't touch the pointy side! They're usually found in sets of three, but that's not a steadfast rule. Sometimes they're just lying out in the open, and sometimes they pop in and out of the ground (or the ceiling, or the walls).
Jump on the button to cause a change in the nearby scenery, usually necessary to proceed.
Large, oxygen-filled bubbles periodically rise from these clusters: tag one to fill Sonic's lungs with air and prolong the time you can spend underwater. Sonic can only spend 30 seconds underwater without drowning, and grabbing a bubble resets the timer. (Labyrinth Zone and Scrap Brain Zone Act 3 only)
As you approach the bonus plate at the end of an Act, leap into the air to find invisible bonus points that are added to your score. They can be worth 100, 1000, or a sweet 10,000.
These signs can be found at the end of each first and second Act. Cross them to Goal end the stage.
These giant Rings appear above bonus plates when you cross with at least 50 Rings on hand. Jump in to warp to the Special Zone. (Once you've collected all 6 Chaos Emeralds, the Warp Rings no longer appear.) If Sonic does not jump in before the bonus plate stops spinning, he will uncontrollably run off of the screen and the Special Zone is lost.
These are found at the Goal end of each third Act, after defeating the boss. Push the button on top to destroy the machine and free the helpless animals within.
Push left or right on the D-pad to initiate Sonic's movement in either direction. As you hold the button down, Sonic gains speed.
Begin walking and hold down the button to make Sonic gain speed. After a few seconds, he'll break into a run.
While running, quickly press and hold the opposite direction on the D-pad to make Sonic screech to a halt. He'll skid for a short distance, based on how fast he was moving.
While standing still, press up on the D-pad to make Sonic gaze to the sky. As you hold up, the camera pans upward, giving you a view of Sonic's overhead surroundings.
While standing still, press down on the D-pad to make Sonic duck down. As you hold down, the camera pans downward, giving you a view of the stage beneath where Sonic stands.
While moving, press down on the D-pad to make Sonic curl into a rolling attack. He'll remain in this position until you jump or slow down. The speed of Sonic's movement while in spin mode is based on how fast you're moving when you launch it, and also on the terrain Sonic rolls along.
Press any button at any time to make Sonic leap into the air with a spin attack. The height of the jump is proportional to how long you hold the button down.
Certain blocks can be pushed by running up against them. Continue holding the D-pad against the offending cube to have Sonic push it along the ground.
Beetle bots that roll innocently along the ground.
Bee bots that fly across from the right side of the screen, pausing once to fire a large flashing projectile downward.
Rabbit robots that just bounce around. These badniks weren't used in the original release of Sonic 1, but appeared in beta releases of the said game.
Piranha bots that leap upward from beneath bridges.
Crab bots that crawl along the ground and fire projectiles from their pincers.
These chameleon bots hang out on the side of cliffs and remain invisible until approached. They come in two flavors: blue ones transform into missiles and jet along the ground. Green ones appear just long enough to fire an energy blast at Sonic.
Caterpillar bots that crawl slowly along the ground. The safest method of disposal is to roll into their spherical heads: venture a poke anywhere else and you'll sustain damage and send their segments flying.
Bat bots that latch onto ceilings until approached, then drop down and fly through the air a short distance before returning to their roost.
Armadillo bots that roll down long slopes after Sonic. They tumble faster than Sonic runs, so leap to avoid being steamrolled. At the bottom of the hill, Roller pauses and briefly opens up: this is your only chance to attack.
Hermit crab bots that crawl along the ground. Their shells are cloaked with spikes, making them invulnerable from above.
Mole bots that spring from below ground and roll along the surface. Look for their drill bit noses poking out of the earth to avoid an ambush.
Piranha bots that swim around underwater.
Irritable sphere bots that hover around very slowly. They're orbited by 4 spiked balls which they fling off in rapid succession upon being approached. It's a dangerous assault, but once it's done, Unidus is completely open to attack.
These guys, palette aside, look exactly like Unidus. They're a bit more cool-headed, though, and won't fire off their barrier of orbs. While this means you don't have that tricky attack to avoid, they're virtually impossible to hit.
Mindless bots that waddle along the ground or ceiling and explode into a shower of projectiles when approached. They can't be damaged, only avoided.
Pig bots that hop in place atop steep banks and roll balls down the slope.
If Sonic finishes the first or second act of any of the first five zones with at least 50 rings, a Warp Ring will appear. If he jumps into it, he will enter a "Special Stage" that hides a Chaos Emerald. In these stages, Sonic, in ball form, falls through a series of rotating mazes.
If he can avoid the "GOAL" signs along parts of the stage's walls (presumably labelled "GOAL" to entice the player into a failed attempt at getting a Chaos Emerald), he will eventually find the Chaos Emerald encased in colored diamonds; touching the diamonds repeatedly will cause them to change color from blue, to green, to yellow, to pink and ultimately disappear, allowing access to the Emerald. The stage will end when Sonic either touches the Emerald or hits a "GOAL" sign. If 50 rings are collected before Sonic makes contact with a "GOAL" sign or gets the Chaos Emerald, then a 'Continue' will be awarded to the player, indicated by a brief, distinct change in melody. Many fans believe that Super Sonic does not appear in Sonic the Hedgehog because 7 Chaos Emeralds are required to transform, whereas this game has only 6.
There are a total of ten opportunities to get Chaos Emeralds, meaning the player can fail a Special Stage up to four times if all six Emeralds are to be collected before the end of the game. Scrap Brain Zone Act 1 will not have a large ring at the end of it, even when finishing with 50 rings, despite the act ending like any of the Act 1s before it.
If the player fails a stage, that stage is skipped and is returned to after attempting the sixth and final Special Stage.
An oddity with the Special Stages is that it is stated in the US manual that 1up items can be found in Special Stages, but they are not seen anywhere. It is possible, however, to earn extra lives by collecting 100 rings in a single stage, indicated by the same sound used in the main zones.
At the end of the third Act of each Zone (except the Scrap Brain Zone), Sonic faces off against Robotnik, who is piloting one of his Egg-O-Matic. For each battle, Robotnik's machine has a different design. Sonic must hit each boss 8 times to destroy it.